In growing cultures in incubator jars, it has been the customary practice to place the jar under positive pressure by means of a gas, either generated from a pellet or being provided in a flow-through process, which displaces the air or eliminates oxygen in the jar to thereby promote the growth of the cultures. Because of these practices, a dangerous pressure build-up could occur in the jar which might break the jar or force the lid off the jar. Some attempts have been made to evacuate the jar but these have been not too successful and require a laboratory vacuum pump which is permanently installed.
Prior art references pertinent to this subject are the following U.S. Pat. Nos. 2,463,143, 3,483,089 and 3,562,114. A reference from a periodical is also pertinent, this reference being entitled "An Anaerobic Culturing And Sampling Apparatus", Canadian Journal of Microbiology, Vol. 11, Pages 597 and 598 (1965).
None of the patents or the reference shows or suggests a simple incubation apparatus which is portable and which uses negative pressure at all times during operation. While U.S. Pat. No. 3,562,114 and the above periodical reference mention the use of vacuum, they do not teach or suggest a simple and expeditious manner of providing a culture jar which can be quickly and easily evacuated but suggest such a jar which depends upon a cumbersome, permanently installed vacuum system.